I tried Stolen Strategy, I wanted to test the new behavior for token copies. That resulted in strange behavior from Stolen Strategy making two tokens instead of one on the first cast, but after testing in match #257912835 Game #834757940 of (solitaire) commander with more Cipher cards, the issue appears to come from the Cipher mechanic and not copying double-faced tokens.
When casting a spell with Cipher from hand, before it even resolves, the spell's effect applies and the player is prompted with a choice asking them if they want to use cipher. Once it does, if the player casts any spell (instant or flash) or has any abilities activated or triggered, they'll be prompted to choose a creature to encode the spell onto, which if done will encode the original Cipher spell off the stack before it even resolves. If they don't do anything in this window, the Cipher spell resolves normally, performing its effects AGAIN and prompting players to encode with Cipher. The next effect on the stack will also prompt the player to encode, but that will be without effect.
In practice, this allows every Cipher spell to double their effect while also dodging countermagic by performing their effect immediately on cast then another time on resolving. With Hidden Strings being part of competitive decks, that seems like a very relevant issue.
When casting a spell with Cipher from hand, before it even resolves, the spell's effect applies and the player is prompted with a choice asking them if they want to use cipher. Once it does, if the player casts any spell (instant or flash) or has any abilities activated or triggered, they'll be prompted to choose a creature to encode the spell onto, which if done will encode the original Cipher spell off the stack before it even resolves. If they don't do anything in this window, the Cipher spell resolves normally, performing its effects AGAIN and prompting players to encode with Cipher. The next effect on the stack will also prompt the player to encode, but that will be without effect.
In practice, this allows every Cipher spell to double their effect while also dodging countermagic by performing their effect immediately on cast then another time on resolving. With Hidden Strings being part of competitive decks, that seems like a very relevant issue.